E223 Large eddy simulation of through-flow effects on turbulent heat transfer characteristics in concentric annulus with inner cylinder rotation

2014 ◽  
Vol 2014 (0) ◽  
pp. _E223-1_-_E223-2_
Author(s):  
Akihiro Ohsawa ◽  
Akira Murata ◽  
Kaoru Iwamoto
Keyword(s):  
Heat Transfer ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Heat Transfer Characteristics ◽  
Concentric Annulus ◽  
Eddy Simulation ◽  
Through Flow ◽  
Large Eddy ◽  
Flow Effects ◽  
Cylinder Rotation

Large Eddy Simulation of Through-Flow Effects on Turbulent Heat Transfer Characteristics in Concentric Annulus With Inner Cylinder Rotation

2015 ◽  
Author(s):  
Akihiro Ohsawa ◽  
Akira Murata ◽  
Kaoru Iwamato
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Taylor Vortices ◽  
Eddy Simulation ◽  
Flow Reynolds Number ◽  
Through Flow ◽  
Large Eddy ◽  
Flow Effects

Through-flow effects on turbulent heat transfer in the Taylor-Couette-Poiseuille flow were investigated by using a large eddy simulation. Through-flow Reynolds numbers of 1000 and 4000 under a constant inner-wall rotation speed were examined. Increase of the through-flow Reynolds number caused increase and decrease of the Nusselt numbers at inner and outer walls, respectively. At lower through-flow Reynolds number, the Taylor vortices were observed. On the other hand, at higher through-flow Reynolds number, the Taylor vortices were transformed into streak and spiral-band structures near the inner and outer walls, respectively. These flow structures were clearly visualized by contour surfaces of instantaneous temperature and second invariant of deformation tensor.

Large Eddy Simulation of Turbulent Heat Transfer Around a Circular Cylinder in Crossflow

2007 ◽  
Author(s):  
Sung-Eun Kim ◽  
Hajime Nakamura
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Heat Transfer Characteristics ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Large eddy simulation has been carried out of turbulent flow and heat transfer around a circular cylinder in crossflow at three subcritical Reynolds numbers (Re = 3,900, 10,000, 18,900) where the flow and heat transfer characteristics change rapidly with the Reynolds number. The computations were carried out using a second-order-accurate finite-volume Navier-Stokes solver that permits use of arbitrary unstructured meshes. A fully implicit, non-iterative fractional-step method was employed to advance the solution in time. The subgrid-scale (SGS) turbulent stresses and heat fluxes were modeled using the dynamic Smagorinsky model. The LES predictions were found to be in good agreement with the experimental data of Hajime and Igarashi (2004). The salient features of turbulent heat transfer in subcritical regime such as the laminar thermal boundary layer and the rapid increase with Reynolds number both in the mean and the r.m.s. Nusselt number in the separated region are closely reproduced by the predictions. The numerical results confirmed that the heat transfer characteristics are closely correlated with the structural change in the underlying flow with the Reynolds number.

Large Eddy Simulation of Turbulent Heat Transfer in Curved-Pipe Flow

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Changwoo Kang ◽  
Kyung-Soo Yang
Keyword(s):  
Heat Transfer ◽  
Pipe Flow ◽  
Temperature Fluctuations ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Subgrid Scale ◽  
Curved Pipe ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean

In the present investigation, turbulent heat transfer in fully developed curved-pipe flow has been studied by using large eddy simulation (LES). We consider a fully developed turbulent curved-pipe flow with axially uniform wall heat flux. The friction Reynolds number under consideration is Reτ  = 1000 based on the mean friction velocity and the pipe radius, and the Prandtl number (Pr) is 0.71. To investigate the effects of wall curvature on turbulent flow and heat transfer, we varied the nondimensionalized curvature (δ) from 0.01 to 0.1. Dynamic subgrid-scale models for turbulent subgrid-scale stresses and heat fluxes were employed to close the governing equations. To elucidate the secondary flow structures due to the pipe curvature and their effect on the heat transfer, the mean quantities and various turbulence statistics of the flow and temperature fields are presented, and compared with those of the straight-pipe flow. The friction factor and the mean Nusselt number computed in the present study are in good agreement with the experimental results currently available in the literature. We also present turbulence intensities, skewness and flatness factors of temperature fluctuations, and cross-correlations of velocity and temperature fluctuations. In addition, we report the results of an octant analysis to clarify the correlation between near-wall turbulence structures and temperature fluctuation in the vicinity of the pipe wall. Based on our results, we attempt to clarify the effects of the pipe curvature on turbulent heat transfer. Our LES provides researchers and engineers with useful data to understand the heat-transfer mechanisms in turbulent curved-pipe flow, which has numerous applications in engineering.

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